The present invention relates generally to a boiler, and specifically to a once-through firetube boiler for generating steam and/or hot water.
Most buildings have a system for generating heat, and for distributing heat throughout the internal portions of the building. One method by which a building can be heated is by circulating steam or hot water through pipes in the building. A system that operates by this method is commonly referred to as a xe2x80x9chydronicxe2x80x9d heating system. Hydronic heating systems typically employ a heat exchanger (e.g. a boiler) to generate the steam or hot water.
One type of boiler, commonly referred to as a xe2x80x9cfiretubexe2x80x9d boiler, generates a hot flue gas, and passes the flue gas through firetubes that extend through a water-filled closed vessel. As the flue gas passes through the firetubes, heat is transferred by convection and radiation from the flue gas to the water, thus generating heated water or steam. The heated water or steam is then extracted from the top of the boiler, and transferred throughout the building through a series of pipes. As the hot water or steam passes through the pipes throughout the building, heat is transferred from the water or steam to the air surrounding the pipes, thus heating the building.
Conventional boilers typically include several arrangements or bundles of firetubes through which the flue gas travels back and forth. For example, if a boiler includes two bundles of firetubes, the flue gas passes in one direction through a first bundle of firetubes, and then in an opposite direction through a second bundle of firetubes. This type of arrangement is commonly referred to as a xe2x80x9ctwo-passxe2x80x9d boiler. Generally, the flue gas is formed in a combustion chamber in heat transfer relationship with the water that is located near the bottom of the vessel. Flue gas is directed from the combustion chamber through the firetubes in a generally upward direction. As the flue gas travels upward through the firetubes, the flue gas cools.
However, conventional firetube boilers are inadequate for heating a building in a short amount of time, because all of the water in the vessel must be heated to a certain temperature before steam forms, or before the water is of a sufficient temperature to heat the building. Also, far more water may be heated than is necessary to heat the building to the desired temperature, thus wasting fuel. Furthermore, conventional firetube boilers are, inadequate for maintaining the heat in a building within a narrow temperature range, because once the desired temperature within the building is reached, a conventional boiler will often continue to output steam or hot water long after flue gas has ceased to flow through the firetubes. This is due to the fact that all of the water in the boiler must cool to a certain temperature before steam or hot water output ceases.
Therefore, it is a first object of the present invention to provide an apparatus for heating a building in a relatively short amount of time.
Another object of the present invention is to provide a hydronic heating system capable of providing steam or hot water in a relatively short amount of time.
Yet another object of the present invention is to provide a boiler capable of maintaining the temperature within a building within a narrow temperature range.
An additional object of the present invention is to provide a boiler having a combustion chamber located proximal to the main steam or water outlet.
Yet another object of the present invention is to provide a boiler that has dividers positioned within the vessel for impeding the flow of water contained therein.
It is a further object of the present invention is to provide a boiler that has a low cost of operation, and is easy and economical to manufacture.
The above-listed objects are met or exceeded by the present apparatus for to generating steam and/or hot water heating water using a heated gas. A boiler is provided having a tank for holding the water. Steam or hot water is extracted from the boiler through an outlet located proximal to the top of the tank, and cooled water returns to the boiler through an inlet located proximal to the bottom of the tank.
A substantially horizontal combustion conduit in heat transfer relationship with the water extends through the tank proximal to the outlet. A heat source in communication with the combustion conduit heats and drives the heated gas into the combustion conduit. A set of substantially horizontal fire conduits in communication with the combustion conduit extend though said tank below the combustion conduit, in heat transfer relationship with the water. When the heated gas is driven into the combustion conduit in a first direction, the heated gas flows through the combustion conduit, flows down and into the fire conduits, and then flows through the fire conduits in a second substantially transverse direction, and heat is transferred to the water as the heated gas flows through the combustion conduit and the fire conduits.